1. Field of the Invention
This invention relates to materials extracted from plants. More particularly, this invention relates to biologically active materials extracted from the plant Maytenus nemerosa (Eckl & Zeyh) Morais (Celastraceae) South Africa and a method of obtaining such materials.
2. Description of the Prior Art
Crude extracts from plants have been used to treat diseases in humans for centuries. Recently, attempts have been made to extract and isolate pure tumor inhibiting compounds from plants. See, for example, S. M. Kupchan, "Novel plant-derived tumor inhibitors and their mechanisms of action," Cancer Treat Rep 60: 1115-1126 (1976). According to Kupchan, to obtain the desired extract, the plant is coarsely ground and subjected to extraction with a hot solvent in a Soxhlet apparatus. The temperature at which the extraction is conducted is higher than room temperature, but usually below 40.degree. C. The solvents most often used in such an extraction process include petroleum ether and methanol. The so-obtained crude extract is subjected to further processing (such as fractionation) to yield an extract of higher purity. p In an alternative method, the plant may be extracted in a percolation apparatus with an acceptable solvent. This extraction method is also conducted at a temperature higher than room temperature, but usually below 40.degree. C. The crude extract is also subjected to further processing to yield a product of higher purity.
As noted above, it is the normal procedure to extract plants using hot solvents. However, it is the present inventor's belief that extraction under heat is undesirable since some of the biologically active materials in the plant may be destroyed and lose its activity as a result of heating.
Furthermore, in conventional processes, a single solvent is used to extract the plant to produce a crude extract which is then purified. Since a single solvent cannot be expected to be capable of extracting all of the active materials in the plant, it can be reasonably concluded that active materials still remain in the plant after extraction by one solvent. Thus, conventional extraction processes suffer from the disadvantages that part of the active materials to be extracted from the plant is either destroyed by heat or remains unextracted. Clearly, such conventional processes are inefficient.